Effects of mouse utricle stromal tissues on hair cell induction from induced pluripotent stem cells

BACKGROUND: Hair cells are important for maintaining our sense of hearing and balance. However, they are difficult to regenerate in mammals once they are lost. Clarification of the molecular mechanisms underlying inner ear disorders is also impeded by the anatomical limitation of experimental access to the human inner ear. Therefore, the generation of hair cells, possibly from induced pluripotent stem (iPS) cells, is important for regenerative therapy and studies of inner ear diseases. RESULTS: We generated hair cells from mouse iPS cells using an established stepwise induction protocol. First, iPS cells were differentiated into the ectodermal lineage by floating culture. Next, they were treated with basic fibroblast growth factor to induce otic progenitor cells. Finally, the cells were co-cultured with three kinds of mouse utricle tissues: stromal tissue, stromal tissue + sensory epithelium, and the extracellular matrix of stromal tissue. Hair cell-like cells were successfully generated from iPS cells using mouse utricle stromal tissues. However, no hair cell-like cells with hair bundle-like structures were formed using other tissues. CONCLUSIONS: Hair cell-like cells were induced from mouse iPS cells using mouse utricle stromal tissues. Certain soluble factors from mouse utricle stromal cells might be important for induction of hair cells from iPS cells

A Novel RNA Synthesis Inhibitor, STK160830, Has Negligible DNA-Intercalating Activity for Triggering A p53 Response, and Can Inhibit p53-Dependent Apoptosis

RNA synthesis inhibitors and protein synthesis inhibitors are useful for investigating whether biological events with unknown mechanisms require transcription or translation; however, the dependence of RNA synthesis has been difficult to verify because many RNA synthesis inhibitors cause adverse events that trigger a p53 response. In this study, we screened a library containing 9600 core compounds and obtained STK160830 that shows anti-apoptotic effects in irradiated wild-type-p53-bearing human T-cell leukemia MOLT-4 cells and murine thymocytes. In many of the p53-impaired cells and p53-knockdown cells tested, STK160830 did not show a remarkable anti-apoptotic effect, suggesting that the anti-apoptotic activity is p53-dependent. In the expression analysis of p53, p53-target gene products, and reference proteins by immunoblotting, STK160830 down-regulated the expression of many of the proteins examined, and the downregulation correlated strongly with its inhibitory effect on cell death. mRNA expression analyses by qPCR and nascent RNA capture kit revealed that STK160830 showed a decreased mRNA expression, which was similar to that induced by the RNA synthesis inhibitor actinomycin D but differed to some extent. Furthermore, unlike other RNA synthesis inhibitors such as actinomycin D, p53 accumulation by STK160830 alone was negligible, and a DNA melting-curve analysis showed very weak DNA-intercalating activity, indicating that STK160830 is a useful inhibitor for RNA synthesis without triggering p53-mediated damage responses

Cbl-b DEFICIENCY AND MACROPHAGE ACTIVATION

We previously reported the potential involvement of casitas B-cell lymphoma-b (Cbl-b) in aging-related murine insulin resistance. Because obesity also induces macrophage recruitment into adipose tissue, we elucidated here the role of Cbl-b in obesity-related insulin resistance. Cbl-b+/+ and Cbl-b-/- mice were fed a high-fat diet (HFD) and then examined for obesity-related changes in insulin signaling. The HFD caused recruitment of macrophages into adipose tissue and increased inflammatory reaction in Cbl-b-/- compared with Cbl-b+/+ mice. Peritoneal macrophages from Cbl-b-/- mice and Cbl-b–overexpressing RAW264.7 macrophages were used to examine the direct effect of saturated fatty acids (FAs) on macrophage activation. In macrophages, Cbl-b suppressed saturated FA-induced Toll-like receptor 4 (TLR4) signaling by ubiquitination and degradation of TLR4. The physiological role of Cbl-b in vivo was also examined by bone marrow transplantation and Eritoran, a TLR4 antagonist. Hematopoietic cell-specific depletion of the Cbl-b gene induced disturbed responses on insulin and glucose tolerance tests. Blockade of TLR4 signaling by Eritoran reduced fasting blood glucose and serum interleukin-6 levels in obese Cbl-b-/- mice. These results suggest that Cbl-b deficiency could exaggerate HFD-induced insulin resistance through saturated FA-mediated macrophage activation. Therefore, inhibition of TLR4 signaling is an attractive therapeutic strategy for treatment of obesity-related insulin resistance

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements